Russia's embassy in Kiev sent a note of protest to Ukraine's foreign ministry on Sunday about attacks on the embassy's cars, the RIA news agency quoted embassy spokesman Oleg Grishin as saying.
Grishin said three cars parked outside the embassy were "seriously damaged" overnight by a group of unidentified people who also threw flares and smoke flares to the embassy.
Kiev police said it had started a criminal investigation into the case which it preliminarily described as hooliganism.
"At night ... unidentified people started smashing parked cars, so a total of three vehicles were damaged: mirrors and the glass had been shattered," the police said in a statement.
A video with a slogan "Freedom to Nadia Savchenko" and footage of few men smashing cars in darkness appeared on the Internet, while hundreds of people have massed near the embassy in Ukraine's capital on Sunday with similar slogans.